Richard J Telford
Biographic Data
| ID | 6370181 |
|---|---|
| NAME | Richard J Telford |
| GIVEN NAMES | Richard J |
| FAMILY NAME | Telford |
| SIGNATURE | TELFORD R J |
| AFFILIATIONS | Bjerknes Centre for Climate Research |
| ORCID | 0000-0001-9826-3076 |
| VERIFIED | Yes |
| TOTAL WORKS | 17 |
| TOTAL CITATIONS | 110 |
| WORKS AS AUTHOR | 17 |
| WORKS AS EDITOR | 0 |
| FIRST PUBLICATION YEAR | 1999 |
| LATEST PUBLICATION YEAR | 2021 |
| H-INDEX | 4 |
Hydrographic shifts south of Australia over the last deglaciation and possible interhemispheric linkages
Northern and southern hemispheric influences—particularly changes in Southern Hemisphere westerly winds (SSW) and Southern Ocean ventilation—triggered the stepwise atmospheric CO 2 increase that accompanied the last deglaciation. One approach for gaining potential insights into past changes in SWW/CO 2 upwelling is to reconstruct the positions of the northern oceanic fronts associated with the Antarctic Circumpolar Current. Using two deep-sea cor…
Multiscale mapping of plant functional groups and plant traits in the High Arctic using field spectroscopy, UAV imagery and Sentinel-2A data
The Arctic is warming twice as fast as the rest of the planet, leading to rapid changes in species composition and plant functional trait variation. Landscape-level maps of vegetation composition and trait distributions are required to expand spatially-limited plot studies, overcome sampling biases associated with the most accessible research areas, and create baselines from which to monitor environmental change. Unmanned aerial vehicles (UAVs) h…
Northward oceanic heat transport in the main branch of the Norwegian Atlantic Current over the late Holocene
The Norwegian Atlantic Current represents the northernmost reaches of the (sub)surface limb of the Atlantic Meridional Overturning Circulation. Its shelf-edge branch, the Norwegian Atlantic Slope Current (NwASC), is of particular interest as it seems to be the main conduit for advected heat towards the Arctic. The objective of this study was to investigate northward oceanic heat transport in the NwASC on longer, geologically meaningful time scale…
All age–depth models are wrong, but are getting better
The construction of accurate age–depth relationships and a realistic assessment of their uncertainties is one of the fundamental prerequisites for comparing and correlating late Quaternary stratigraphical proxy records. Four widely used age–depth modelling routines – CLAM, OxCal, Bacon and Bchron – were tested using radiocarbon dates simulated from varved sediment stratigraphies. All methods produce mean age–depth models that are close to the tru…
East Asian summer monsoon precipitation variability since the last deglaciation
The lack of a precisely-dated, unequivocal climate proxy from northern China, where precipitation variability is traditionally considered as an East Asian summer monsoon (EASM) indicator, impedes our understanding of the behaviour and dynamics of the EASM. Here we present a well-dated, pollen-based, ~20-yr-resolution quantitative precipitation reconstruction (derived using a transfer function) from an alpine lake in North China, which provides fo…
Taxon selection using statistical learning techniques to improve transfer function prediction
Transfer functions are widely used in palaeoecology to provide quantitative environmental reconstructions using biological proxies. Most models use all but the rarest taxa present in the training set, even though many may be unrelated to the environmental variable of interest. We hypothesise that retaining such non-informative taxa will reduce model robustness and present a method for variable selection motivated by the statistical learning algor…
Is palaeoecology a ‘special branch’ of ecology
Palaeoecology and ecology have a lot in common. However, the two disciplines have evolved almost separately, leading to an ongoing debate on how to link them better, as both would undoubtedly benefit from a higher degree of cross-fertilisation of ideas, research insights and questions. In this paper, we explore similarities and differences in the two branches of ecology over the past 40 years by assessing the publication output from an unusually …
Significance tests for transfer function-derived quantit-ative reconstructions
Testing peatland testate amoeba transfer functions
Transfer functions are widely used in palaeoecology to infer past environmental conditions from fossil remains of many groups of organisms. In contrast to traditional training-set design with one observation per site, some training-sets, including those for peatland testate amoeba-hydrology transfer functions, have a clustered structure with many observations from each site. Here we show that this clustered design causes standard performance stat…
Comparing different calibration methods (WA/WA-PLS regression and Bayesian modelling) and different-sized calibration sets in pollen-based quantitative climate reconstruction
We compare a Bayesian modelling-based technique with weighted averaging (WA) and weighted averaging-partial least squares (WA-PLS) regression in pollen-based summer temperature transfer function calibration. We test the methods using a new, 113-sample calibration set from Estonia, Lithuania and European Russia, and a Holocene fossil pollen sequence from Lake Kharinei, a previously studied lake in northeast European Russia. We find WA-PLS to outpe…
Last nine-thousand years of temperature variability in Northern Europe
The threat of future global warming has generated a major interest in quantifying past climate variability on centennial and millennial time-scales. However, palaeoclimatological records are often noisy and arguments about past variability are only possible if they are based on reproducible features in several reliably dated datasets. Here we focus on the last 9000 years, explore the results of 36 Holocene pollen-based July mean and annual mean t…
Oxygen and carbon isotope composition of authigenic carbonate from an Ethiopian lake
The oxygen and carbon isotope composition of sedimentary carbonates formed in Lake Hayq, a closed-basin lake in northern Ethiopia, suggests marked variation in the balance between precipitation and evaporation during the last 2000 years. Diatom stratigraphy shows that the lake remained deep enough to support planktonic taxa, and was never saline. The record suggests that rainfall was higher than that of the twentieth century during most of this t…
Relationships between calibrated ages and depth in stratigraphical sequences
We present a procedure for estimating age-depth relationships in stratigraphical sequences by means of a generalized mixed-effect regression using an ancillary function for the partitioning of the fixed effect and the random effect corresponding to the degree of representativity of the individual calibrated dates for a particular section of the sedimentary sequence. The procedure uses mid-point estimates of the calibrated ages in combination with…
All age–depth models are wrong
The intercept is a poor estimate of a calibrated radiocarbon age
Intercept-based methods of generating a point estimate of a calibrated radiocarbon date are very popular, but exhibit undesirable behaviour. They are highly sensitive to the mean of the radiocarbon date and to adjustments of the calibration curve. Other methods give more stable results. The weighted average of the probability distribution function is recommended as the best central-point estimate, but more consideration should be given to using t…
The sensitivity of a Tanzanian crater lake to catastrophic tephra input and four millennia of climate change
Diatom genera in many large East African lakes change little throughout the Holocene period suggesting relatively stable ecological conditions and some resilience to environmental change. Ecosystem stability is less common in smaller, more sensitive lakes, such as those within volcanic craters, where external impacts can cause abrupt and rapid fluctuations. A 4100-year diatom and cyanobacteria pigment record from Lake Massoko, a volcanic crater l…
Groundwater-Mediated Response to Holocene Climatic Change Recorded by the Diatom Stratigraphy of an Ethiopian Crater Lake
The diatom stratigraphy of a 23-m sediment core from Lake Tilo, a maar lake in the Ethiopian Rift Valley, provides a 10,000-yr record of lake salinity and trophic status. Until 5500 14 C yr B.P., the phytoplankton was dominated by Aulacoseira granulata, with only minor changes in the abundance of other diatoms; the lake was over 50 m deep, eutrophic, and oligosaline. At 5500 yr B.P., geothermal groundwater inflow, inferred from calcite and silica…
The intercept is a poor estimate of a calibrated radiocarbon age
Intercept-based methods of generating a point estimate of a calibrated radiocarbon date are very popular, but exhibit undesirable behaviour. They are highly sensitive to the mean of the radiocarbon date and to adjustments of the calibration curve. Other methods give more stable results. The weighted average of the probability distribution function is recommended as the best central-point estimate, but more consideration should be given to using t…
Relationships between calibrated ages and depth in stratigraphical sequences
We present a procedure for estimating age-depth relationships in stratigraphical sequences by means of a generalized mixed-effect regression using an ancillary function for the partitioning of the fixed effect and the random effect corresponding to the degree of representativity of the individual calibrated dates for a particular section of the sedimentary sequence. The procedure uses mid-point estimates of the calibrated ages in combination with…
All age–depth models are wrong, but are getting better
The construction of accurate age–depth relationships and a realistic assessment of their uncertainties is one of the fundamental prerequisites for comparing and correlating late Quaternary stratigraphical proxy records. Four widely used age–depth modelling routines – CLAM, OxCal, Bacon and Bchron – were tested using radiocarbon dates simulated from varved sediment stratigraphies. All methods produce mean age–depth models that are close to the tru…
Oxygen and carbon isotope composition of authigenic carbonate from an Ethiopian lake
The oxygen and carbon isotope composition of sedimentary carbonates formed in Lake Hayq, a closed-basin lake in northern Ethiopia, suggests marked variation in the balance between precipitation and evaporation during the last 2000 years. Diatom stratigraphy shows that the lake remained deep enough to support planktonic taxa, and was never saline. The record suggests that rainfall was higher than that of the twentieth century during most of this t…
Comparing different calibration methods (WA/WA-PLS regression and Bayesian modelling) and different-sized calibration sets in pollen-based quantitative climate reconstruction
We compare a Bayesian modelling-based technique with weighted averaging (WA) and weighted averaging-partial least squares (WA-PLS) regression in pollen-based summer temperature transfer function calibration. We test the methods using a new, 113-sample calibration set from Estonia, Lithuania and European Russia, and a Holocene fossil pollen sequence from Lake Kharinei, a previously studied lake in northeast European Russia. We find WA-PLS to outpe…
The sensitivity of a Tanzanian crater lake to catastrophic tephra input and four millennia of climate change
Diatom genera in many large East African lakes change little throughout the Holocene period suggesting relatively stable ecological conditions and some resilience to environmental change. Ecosystem stability is less common in smaller, more sensitive lakes, such as those within volcanic craters, where external impacts can cause abrupt and rapid fluctuations. A 4100-year diatom and cyanobacteria pigment record from Lake Massoko, a volcanic crater l…
Is palaeoecology a ‘special branch’ of ecology
Palaeoecology and ecology have a lot in common. However, the two disciplines have evolved almost separately, leading to an ongoing debate on how to link them better, as both would undoubtedly benefit from a higher degree of cross-fertilisation of ideas, research insights and questions. In this paper, we explore similarities and differences in the two branches of ecology over the past 40 years by assessing the publication output from an unusually …
Testing peatland testate amoeba transfer functions
Transfer functions are widely used in palaeoecology to infer past environmental conditions from fossil remains of many groups of organisms. In contrast to traditional training-set design with one observation per site, some training-sets, including those for peatland testate amoeba-hydrology transfer functions, have a clustered structure with many observations from each site. Here we show that this clustered design causes standard performance stat…
Groundwater-Mediated Response to Holocene Climatic Change Recorded by the Diatom Stratigraphy of an Ethiopian Crater Lake
The diatom stratigraphy of a 23-m sediment core from Lake Tilo, a maar lake in the Ethiopian Rift Valley, provides a 10,000-yr record of lake salinity and trophic status. Until 5500 14 C yr B.P., the phytoplankton was dominated by Aulacoseira granulata, with only minor changes in the abundance of other diatoms; the lake was over 50 m deep, eutrophic, and oligosaline. At 5500 yr B.P., geothermal groundwater inflow, inferred from calcite and silica…
The sensitivity of a Tanzanian crater lake to catastrophic tephra input and four millennia of climate change
Diatom genera in many large East African lakes change little throughout the Holocene period suggesting relatively stable ecological conditions and some resilience to environmental change. Ecosystem stability is less common in smaller, more sensitive lakes, such as those within volcanic craters, where external impacts can cause abrupt and rapid fluctuations. A 4100-year diatom and cyanobacteria pigment record from Lake Massoko, a volcanic crater l…
All age–depth models are wrong
The intercept is a poor estimate of a calibrated radiocarbon age
Intercept-based methods of generating a point estimate of a calibrated radiocarbon date are very popular, but exhibit undesirable behaviour. They are highly sensitive to the mean of the radiocarbon date and to adjustments of the calibration curve. Other methods give more stable results. The weighted average of the probability distribution function is recommended as the best central-point estimate, but more consideration should be given to using t…
Relationships between calibrated ages and depth in stratigraphical sequences
We present a procedure for estimating age-depth relationships in stratigraphical sequences by means of a generalized mixed-effect regression using an ancillary function for the partitioning of the fixed effect and the random effect corresponding to the degree of representativity of the individual calibrated dates for a particular section of the sedimentary sequence. The procedure uses mid-point estimates of the calibrated ages in combination with…
Oxygen and carbon isotope composition of authigenic carbonate from an Ethiopian lake
The oxygen and carbon isotope composition of sedimentary carbonates formed in Lake Hayq, a closed-basin lake in northern Ethiopia, suggests marked variation in the balance between precipitation and evaporation during the last 2000 years. Diatom stratigraphy shows that the lake remained deep enough to support planktonic taxa, and was never saline. The record suggests that rainfall was higher than that of the twentieth century during most of this t…
Last nine-thousand years of temperature variability in Northern Europe
The threat of future global warming has generated a major interest in quantifying past climate variability on centennial and millennial time-scales. However, palaeoclimatological records are often noisy and arguments about past variability are only possible if they are based on reproducible features in several reliably dated datasets. Here we focus on the last 9000 years, explore the results of 36 Holocene pollen-based July mean and annual mean t…
Testing peatland testate amoeba transfer functions
Transfer functions are widely used in palaeoecology to infer past environmental conditions from fossil remains of many groups of organisms. In contrast to traditional training-set design with one observation per site, some training-sets, including those for peatland testate amoeba-hydrology transfer functions, have a clustered structure with many observations from each site. Here we show that this clustered design causes standard performance stat…
Comparing different calibration methods (WA/WA-PLS regression and Bayesian modelling) and different-sized calibration sets in pollen-based quantitative climate reconstruction
We compare a Bayesian modelling-based technique with weighted averaging (WA) and weighted averaging-partial least squares (WA-PLS) regression in pollen-based summer temperature transfer function calibration. We test the methods using a new, 113-sample calibration set from Estonia, Lithuania and European Russia, and a Holocene fossil pollen sequence from Lake Kharinei, a previously studied lake in northeast European Russia. We find WA-PLS to outpe…
Significance tests for transfer function-derived quantit-ative reconstructions
Taxon selection using statistical learning techniques to improve transfer function prediction
Transfer functions are widely used in palaeoecology to provide quantitative environmental reconstructions using biological proxies. Most models use all but the rarest taxa present in the training set, even though many may be unrelated to the environmental variable of interest. We hypothesise that retaining such non-informative taxa will reduce model robustness and present a method for variable selection motivated by the statistical learning algor…
Is palaeoecology a ‘special branch’ of ecology
Palaeoecology and ecology have a lot in common. However, the two disciplines have evolved almost separately, leading to an ongoing debate on how to link them better, as both would undoubtedly benefit from a higher degree of cross-fertilisation of ideas, research insights and questions. In this paper, we explore similarities and differences in the two branches of ecology over the past 40 years by assessing the publication output from an unusually …
East Asian summer monsoon precipitation variability since the last deglaciation
The lack of a precisely-dated, unequivocal climate proxy from northern China, where precipitation variability is traditionally considered as an East Asian summer monsoon (EASM) indicator, impedes our understanding of the behaviour and dynamics of the EASM. Here we present a well-dated, pollen-based, ~20-yr-resolution quantitative precipitation reconstruction (derived using a transfer function) from an alpine lake in North China, which provides fo…
All age–depth models are wrong, but are getting better
The construction of accurate age–depth relationships and a realistic assessment of their uncertainties is one of the fundamental prerequisites for comparing and correlating late Quaternary stratigraphical proxy records. Four widely used age–depth modelling routines – CLAM, OxCal, Bacon and Bchron – were tested using radiocarbon dates simulated from varved sediment stratigraphies. All methods produce mean age–depth models that are close to the tru…
Northward oceanic heat transport in the main branch of the Norwegian Atlantic Current over the late Holocene
The Norwegian Atlantic Current represents the northernmost reaches of the (sub)surface limb of the Atlantic Meridional Overturning Circulation. Its shelf-edge branch, the Norwegian Atlantic Slope Current (NwASC), is of particular interest as it seems to be the main conduit for advected heat towards the Arctic. The objective of this study was to investigate northward oceanic heat transport in the NwASC on longer, geologically meaningful time scale…
Hydrographic shifts south of Australia over the last deglaciation and possible interhemispheric linkages
Northern and southern hemispheric influences—particularly changes in Southern Hemisphere westerly winds (SSW) and Southern Ocean ventilation—triggered the stepwise atmospheric CO 2 increase that accompanied the last deglaciation. One approach for gaining potential insights into past changes in SWW/CO 2 upwelling is to reconstruct the positions of the northern oceanic fronts associated with the Antarctic Circumpolar Current. Using two deep-sea cor…
Multiscale mapping of plant functional groups and plant traits in the High Arctic using field spectroscopy, UAV imagery and Sentinel-2A data
The Arctic is warming twice as fast as the rest of the planet, leading to rapid changes in species composition and plant functional trait variation. Landscape-level maps of vegetation composition and trait distributions are required to expand spatially-limited plot studies, overcome sampling biases associated with the most accessible research areas, and create baselines from which to monitor environmental change. Unmanned aerial vehicles (UAVs) h…
Geology and Paleoclimatology Research (14 works) · Geography (8 works) · Physical geography (8 works) · Geological formations and processes (7 works) · Geology (6 works) · Holocene (6 works) · Mathematics (6 works) · Statistics (6 works) · Ecology (5 works) · Geology (5 works)